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Gonioscopy
This document discusses gonioscopy, a clinical technique used to examine the anterior chamber angle. It defines gonioscopy and describes the purpose of performing it, which is to visualize important angle structures. Two main types are described - direct gonioscopy using specialized lenses, and indirect gonioscopy using gonioprisms and a slit lamp. Various lenses and prisms used for each type are outlined. The document also covers gonioscopy techniques, grading systems for angle width, common angle structures seen, and clinical uses of gonioscopy examinations.
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Gonioscopy
- 1. GONIOSCOPY MADE BY :SWATI PANARA FROM : BHARTIMAIYA COLLEGE OF OPTOMETRY 2nd YEAR 4th SEMESTER
- 2. INTROUCTION • THE TERMGONIOSCOPY WAS COINED BY TRANTAS IN 1907. • IT IS A CLINICAL TECHNIQUE THAT IS USED TO EXAMINE STRUCTURE IN THE ANTERIOR CHAMBER ANGLE.
- 3. PURPOSE OF GONIOSCOPY •WHY DO I NEED PERFORM GONIOSCOPY ?? - fundamental part of comprehensive exam. - done initially for all glaucoma patient and suspects. - repeated periodically for patients with angle closure glaucoma.
- 4. • WHAT CANI ACHIEVE WITH GONIOSCOPY ?? - Visualization of anterior chamber angle - view of the peripheral iris - differentiation between angle closure , occludable and secondary glaucoma.
- 5. • WHAT SHOULDI LOOK FOR IN GONIOSCOPY ? - level of iris insertion - shape and profile of peripheral iris - estimated width of the angle approach - degree of trabecular pigmentation - areas of iridotrabecular apposition
- 6. PRINCIPLE • The totalinternal reflection at the cornea occurs because the angle of incidence of the rays from the anterior chamber angle structure is greater than the critical angle of the cornea – air interface , which is approximately 46°
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- 8. DIRECT GONIOSCOPY • Itis performed with a steep convex lens which permits light from the angle to exit the eye closer to the perpendicular at the lens – air interface. • These lenses are used with a operating microscope. • Direct gonioscopy is useful but fairly impractical for routine use.
- 9. TYPES Koeppe goniolens Huskins barkan’slens Swan Jacob's lens Richardson- Shaffer's lens Sieback goniolens Worth goniolens
- 10. KOEEPE LENS • Itis the most commonly used for diagnostic direct gonioscopy.
- 11. HUSKINS BARKAN’S LENS •It is a prototype surgical goniolens used for goniotomy. SWAN JACOB’S LENS • It is also used for surgical purpose.. SIEBACK GONIOLENS • It is a tiny goniolens which floats on the cornea.
- 12. RICHARDSON – SHAFFER’SLENS • It is basically a small Koeppe lens used for infants. WORTH GONIOLENS • It anchors to cornea by partial vacuum. •
- 13. TECHNIQUE • Cornea isfirst anaesthetized with 4% xylocaine instilled topically. • Ideal position – patient lying supine with the examiner sitting on the side of the eye. • Patient looking up , lower lip of the goniolens is inserted below the lower lid. • Patient is asked to look down and upper lip is placed beneath upper lid.
- 15. • Now thepatient’s head turned towards the examiner , the nasal lip of goniolens is slightly raised and normal saline drops are used for irrigation • Now gonioscopy is performed with the patient looking to the ceiling.
- 16. ADVANTAGE • Greater flexibility •Used in goniotomy surgery • Used in anaesthetized patients as in infants • Causes lesser distortion of anterior chamber • angle becomes deep in supine position so it is easy to see the angle. • Panoramic view is obtained so one part of angle could be compared with the other.
- 17. • Using twolenses , both eyes can be examined simultaneously. • Provide a straight view rather than inverted view. • Detailed examination of minor structure is possible.
- 18. DISADVANTAGE • Inconvenient • Annoyinglight reflex from cornea • Time – consuming • Benefits of slit lamp are not available
- 19. INDIRECT GONIOSCOPY • Indirectgonioscopy uses mirrors or prism to over come the problem of total internal reflection. • Moreover , it uses the slit lamp’s illumination and magnification system to its advantage.
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- 22. GOLDMANN THREE MIRROR GONIOPRISM •The mirror having inclination of 59° and domed upper border is used for gonioscopy. • (1) the mirror inclined at 67° is used to examine pars plana area of ciliary body. • (2) the mirror having inclination of 73° is used to examine ora serrata area of peripheral fundus.
- 24. GOLDMANN TWO MIRROR GONIOPRISM •Both the mirrors are inclined at 62° • It need to be rotated once to examine the whole angle. • Laser trabeculoplasty
- 25. GOLDMANN SINGLE MIRROR GONIOPRISM •The mirror is inclined at 62° • It is prototype diagnostic gonioprism. • It is to be rotated three times to examine the whole angle.
- 26. ADVANTAGE OF GOLDMANN GONIOPRISM •Easy to use • Excellent view • Stabilizes the globe and there for can be used in argon laser trabeculoplasty. • Peripheral retina can be seen • Goldman two mirror gives best In – situ view of the angle.
- 27. DISADVANTAGE OF GOLDMANN GONIOPRISM •Curvature of lens is more than that of cornea so a coupling material is required. it blurs vision and fundus therefore field charting , direct and indirect ophthalmoscopy cannot be done immediately after its use. • It cannot be used for indentation gonioscopy. • Only one mirror is there for gonioscopy so it needs to rotated by 360°
- 28. ALLEN – THROPEGONIOPRISM • It has got four prisms instead of mirror and allows examination of the whole angle without rotating the prisms.
- 29. GONIOPRISM NOT REQUIRING COUPLINGAGENT ZEISS FOUR MIRROR GONIOPRISM POSNER GONIOPRISM SUSSMAN LENS TOKEL GONIOPRISM
- 30. ZEISS FOUR MIRRORGONIOPRISM • Four identical mirrors angled at 64° which allow examination without rotation of the lens. • ADVANTAGE : coupling material not required • Easy to perform when mastered • Indentation gonioscopy can be performed • DISADVANTAGE : difficult to master • Does not stabilize the globe
- 32. POSNER LENS • Itis similar to zeiss gonioprism but is made of plastic instead of glass and also has fixed rather than detachable handle.
- 33. TOKEL GONIOPRISM • Itis a single mirror gonioprism and has got a wider field of view. • SUSSMAN LENS • It is also similar to zeiss lens except that it has no handle.
- 35. TECHNIQUE • Eye isanaesthetized with the topical anaesthetic anent • Patient who is sitting on the slit lamp is asked to look down • The thumb of one hand is used to retract the upper lid. • The lower edge of the gonioscope is placed on the lower lid. • Slit lamp beam is focused on the mirror that shows the angle diametrically opposite to it.
- 36. ADVANTAGE • Easier tolearn. • Faster to perform. • Requires less instrumentation and space. • Slit lamp provides better optics and lighting. • Indentation gonioscopy can also be done. • Magnified stereoscopic view of optic disc can also be obtained.
- 37. DISADVANTAGE • Comparison isnot possible. • Limited positioning of light rays. • Difficult to perform in horizontal meridian. • Mirror image seen , so confusing. • Excessive pressure may open or close the angle artefactually.
- 38. RECORDING • Most posteriorangle structure observed. • Angular approach at the recess. • Iris contour • Amount of pigment • to what degree the angle opens with indentation • Surgical alteration such as sclerectomy and peripheral iridotomy.
- 40. GRADING SYSTEM FORTHE ANGLE OF ANTERIOR CHAMBER SCHEIE’S GRADING SHAFFER’S GRADING RP CENTRE GONIOSCOPIC GRADING Speath GONIOSCOPIC GRADING
- 41. SCHEIE’S GRADING • Grade1 narrow = hard to see over iris root into recess • Grade 2 narrow = ciliary body band obscured • Grade 3 narrow = posterior trabeculum obscured • Grade 4 narrow = only schwalbe’s line visible.
- 42. SHAFFER’S GRADING SYSTEM •Grade 0 —PARTIAL OR COMPLETE CLOSURE • Grade I </= 10° angle of approach • Grade II -20° angle of approach • Grade III 20°–35° angle of approach • Grade IV 35 –45 angle of approach
- 44. RP CENTRE GONIOSCOPICGRADING • Grade 0 = no dipping of the beam • Grade 1 = dipping of the beam • Grade 2 = schwalbe’s line and anterior one – third of the trabecular meshwork visualized. • Grade 3 = middle one – third of trabecular meshwork visualized. • Grade 4 = posterior one – third of trabecular meshwork • Grade 5 = scleral spur visualized • Grade 6 = ciliary body band visualized
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- 47. GONIOSCOPIC VIEW OFANGLE STRUCTURE
- 49. SCHWALBE’S LINE • Terminationof descement’s membrane • It is marked only by a slight change in colour from trabecular meshwork or by a faint white line. • Important landmark in identifying the gonioscopic anatomy in confusing angle.
- 51. TRABECULAR MESHWORK • Ithas an anterior non pigmented trabecular meshwork and posterior pigmented trabecular meshwork.
- 52. CILIARY BODY BAND •It is light grey or dark brown just posterior to the scleral spur.
- 53. ROOT OF IRIS •Iris contour is slightly convex or flat. • Colour varies in different individuals.
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- 55. CLINICAL USE OFGONIOSCOPY • Differentiation between primary open angle glaucoma and primary closure angle glaucoma • To diagnose and provide a prognosis for the congenital glaucoma. • To diagnose secondary glaucoma and unusual causes of glaucoma. • For treatment • To diagnose condition like tumours of anterior segment , intraocular foreign body.
- 56. LIMITATION • Cannot beperformed in painful inflamed eyes. • Difficult to perform in case of acute glaucoma where eyes are painful.
- 57. REFERENCE • CLINICAL PROCEDUREIN PRIMARY EYE CARE – DAVID B. ELLIOTT • OPTIC AND REFRACTION – A K KHURANA • NET • PURAB SIR’S NOTES • COMPREHENSIVE OPHTHALMOLOGY – A K KHURANA • KANSKI